Current supply means



Aug. 29, 1933? SCHROTER 1,924,415

CURRENT SUPPLY MEANS Filed July 18, 1929 I/ I :i: W

INVENTORW Lu FRITZ SCH ROTER ATTOR N EY Patented Aug. 29, 1933 CURRENT SUPPLY MEANS Fritz Schriiter, Berlin, Germany, assignor to Telefunken Gesellschaft fur Drahtlose Telegraphic in. b. 11., Berlin, Germany, a corporation of Germany Application July 18, 1929, Serial No. 379,168, and in Germany July 27, 1928 4 Claims.

In large power transmitter tubes especially of the kind in which the outside wall of the tubes consists wholly or partly of metal, the problem of maintaining a constant vacuum is attended ,5 with practical difficulties whenever the vacuum pump is not to be operated constantly. An impairment of the vacuum is liable to lead to puncture, and this in turn may lead to destruction of the transmitter tube by the short-circuitcurrent which starts to fiow when such breakdown happens.

To prevent such an occurrence, attempts have been made to limit the value of the short-circuit current to a permissible value. The breaking down of the tube itself may be accepted, since this will not occasion any substantial impairment of operations, indeed, it may result in an improvementof the vacuum in the tube.

If the plate potential of the transmitter tube network by means of rectification by valves, the

desired end may be insured by underheating (subnormal heating) of the valves whereby the thermionic current and thereby the short-circuit current are limited. However, such underheating of the valves involves the disadvantage that the potential fall of the valve undernormal operating conditions and consequently the plate load are increased, and this tends to reduce the life of the valves.

Another means to limit the short-circuit current consists in inserting protective resistances in series with the tube, separate resistance being suitably provided in series with each tube in case a plurality of tubes are parallel connected. This scheme, however, is very costly since the protective resistance for the plates must be designed so as to be able to stand a large load, they are subject to high potential actions, and the overall efficiency of the equipment is diminished.

Now, according to the present invention a limitation of the short-circuit current isinsured by that the magnetron effect is usedfor the valves, control of the magnetron effect being secured by theplate current itself by'that' the magnetron coil is connected directly in the path of the plate current. The size of this coil should most suitably be regulable in order that fine regulation of current limitation may be feasible, and that the mag- .50 netron eifect may be caused to become operative in accordance with the use of a certain valve type in transmitters of different power.

Two practical applications of the invention have been illustrated in Figures 1 and 2.

Referring to Figure 1', S is a thermionic tube is derived from an alternating current supply of the triode type having an anode 2, cathode 4, and control grid electrode 6. The electrodes 2, 4 and 6 may be connected in alternating current circuits of any type, not shown, by way of leads 1, 3 and 5. Direct current potential for the plate cathode circuit of this tube is supplied from a source 8. The source 8 may be of any type which supplies current, as, for example, alternating current, or rectified alternating current which needs smoothing and/or limiting. In the present case it is assumed to be alternating current which is rectified by the thermionic tube V, which has its anode and cathode impedance connected in series between the anode 2, and cathode 4 by way of a magnetron winding W. Thethermionic tube V 7 is located co-axially with respect to the winding W and within the field of the winding W, as shown.

The magnetron coil in the case of valves with water-cooled plates should preferably be disposed around the metallic plate.

To increase the action it is advantageous t0 insert a capacity between the valve plate and the magnetron coil, as shown in Figure 2, said capacity, and, if desired, also the magnetron coil itself I consisting of part of the low-pass (choke) filter provided for the purpose of eliminating overtones or ripples from the plate direct current potential.

Arrangements, of course, could also be so made that the magnetron coil controlling the, thermionic current is connected above the smoothing filter.

I claim:

1. Means for deriving unidirectional current of a controlled intensity from an alternating current source comprising, a rectifier having a hot electrode and a cold electrode, means for connecting said electrodes with said source, and means for limiting the amount of current passed by said rec tifier comprising a winding in series in said connection, said rectifier being located in the field of said winding, the rectifier and the winding being co-axial so that the elements of the rectifier are" symmetrically located in the field of said winding.

2,. Means for producing unidirectional current from a source of alternating current and supplying a constant amount of such current to a load circuit comprising, a source of alternating current, an inductance/a thermionic rectifier co-axially mounted within said inductance so-that the elements thereof are in the field of said inductance, and means for connecting-said alternating current source, said load, said rectifier, and said in ductance in series, whereby changes in the current nected in alternating current signalling circuits, 7

and means for supplying uni-directional current to the anode of said tube and for limiting the amount supplied thereto comprising, a source of anode current, a thermionic device connected between said source and said anode, a winding in said connection, said winding and said device being co-axial with respect to each other, the electrodes of said device being. located within the field of said winding.

4. An arrangement as claimed in claim 3 in which a capacity is connected in shunt with said winding. u

FRITZ SCHROTER. 

